Alternating-current rectifier.



E; G. BALLMAN.

ALTEENATING CURRENT RECTIFIER.

APPLICATION FILED JAN. 3, 1911.

1,131,896. Patented M21216, 1915.

2 SHEETS-SHEET 1.

g. l Fig.2.

mm 17 L U?- I Edwin QBallman.

E. C. BALLMAN. ALTERNATING UUBRBNT BEGTIFIEE. I APPLIOATIUR FILED JAN. 3, 1911.

Patented Mar. 16, 1915.

Z SHBETS-SHEET 2.

I INVENTOR v Edwin-qBauman,

UNITED STATES PATENT OFFICE.

EDWIN C. BALLMAN, OF ST. LOUIS, MISSOURI, ASSIGNOR TO WAGNER ELECTRIC MANUFACTURING COMPANY, OF ST. LOUIS, MISSOURI, A CORPORATION. OF

MISSOURI.

Application filed January 3, 1911.

tromagnetic devices and its object is to pro-- vide an apparatus "which will transform a current drawn from an alternating supply into current which is unidirectional or in which the impulses in one direction are greater than those in the other. Such a current is particularly adapted to be used for charging storage batteries. In apparatus of the type mentioned it is necessary to use a transformer by means of which the desired voltage may be applied to the terminals of the storage battery and it is the particular object of my invention to so arrange the circuits and connections that when the current from the source is interrupted for any reason or the mains short-circuited, the battery cannot discharge through a short circuit and thus waste'the energy previously stored. The apparatus is also so arranged that a current will be delivered to the storage battery in the proper direction to charge it regardless of which one of its terminals is connected to a given terminal of the char ing circuit.

()t ier objects and advantages of my apparatus will appear from the description which follows.

In the accompanying drawings, Figure l a diagrammatic representation of one form of my im roved rectifier; Fig. 2 shows a slight modi cation in which the impedance is in the charging circuit only. In the apparatus shown in Fig. 3 the alternating and direct currents are supplied to separate coils of the electromagnet. Fig. 4 is a dia- Specification 'of Letters Patent.

ALTEBNATING-GURR-EN'I RECTIFIER.

Patented Mar. 16, 1915. Serial No. 600,429.

mains 1, 2. The secondary winding has a tap S near its middle. nected to the terminal 17 of the storage battery 20 by way of the conductor 18 and the adjustable impedance 13. The terminal S This tap S is conof the secondary winding is connected with s the terminal 16 of the battery 20 through the conductor 14, the coil 10 around the core 9 of the electromagnet and through conductor 15. The terminal S of the secondary winding is adapted to be connected to the terminal 16 of the storage battery 20 through conductor 19, binding-post 4, springs 5 and 11, binding-post l2 and conductor 15. The section of the secondary winding between S and S can discharge into the battery through the impedance 13 while current from the section between S and S can only reach the battery through the impedance l3 and the highly inductive winding of the electromagnet. The part 6,, S, does not carry as much current as the part 8,, S and can therefore be wound with a. smaller wire.

Spring. 5 is held only at the bindin post 4 and is therefore free to vibrate. It is preferably so adjusted as to mass and length that its natural frequency of vibration is greater than the frequency of the alternating current. 6 is a stop which limits its vibration in one direction. Spring 11 carries an iron armature 7 and is supported by binding-post 12, secured to the base of the apparatus. This spring 11 and the mass of the armature 7 attached to it are preferably so adjusted that the vibration of the spring 11 is considerably less than the frequency of the alternating current. The resultant natural frequency of springs 5 and 11, when vibrating in unison, would be a mean of the individual natural frequencies if both vibrating elements had the same mass. In the present combination the mass of spring 11 is by far the greater and the resultant natural frequency of the combination will therefore more nearly approach the natural frequency of vibration of spring 11 than that of spring 5. Thus if the natural frequency of spring 5 is chosen 5% higher than the frequency of the alternating E. M. F. and thatyof spring 11 is chosen 10% lower, then since 11 has more mass than 5 the resultant natural frequency of the two springs vibrating in unison or of a haps lower than that of the alternating E. M. EEZSpring 11 when at rest is out of contact'with spring 5 but when vibrating comes into contact with it and thereby closes the charging circuit. it is necessary for the successful operation of this apparatus, 2'. e. in order to charge the battery and to do so Without undue sparking, that the springs 5 and 11 shall make contact with each other only as long as the alternating E. M. F has a certain direction and exceeds a certain 'magnitude- These conditions are onlv fulfilled during a fractionof one cycleand it is therefore desirable that the period of an actual vibration of the springs be equal to that of the alternating hi. M. F. and that the stop 6 be so adjusted as to suitably limit' the time of contact. For the arrangements of circuits and contacts here described there should be a phase difference of about 180 degrees between the vibrations of the spring and the period of the alternating E. M. 1 Now the actual period of vibration of the spring is controlled by the period of the flux in the core 9 of the electromagnet, whereas the phase relation of the period of vibration of the combined springs 5 and 11 to the period of the flux is determined by the frequency of the natural vibration of the combinaticn of springs as compared to the frequency of the flux. If the frequency of the natural vibration of the combined springs is a little smaller than the frequency of the flux then the vibrations of the springs when the latter are brought within the influence of the flux, will be increased so as to become equal infre'quency to that of the flux, but the phase of said vibrations will lag behind the phase of the flux by an amount dependent on the initial difference of the respective frequencies. If the natural frequency of vibration of the springs is greater than that of the flux, then the frequency of vibration will be diminished by the influence of the flux until it corresponds to that of the flux, but the phase of the said vibrations will lead the phase of the flux vibrations. If the diiference between the natural frequency of the spring combination and the frequency of the flux is too great in either direction, then the springs will not respond to the flux sufficiently to make contact in the manner described. The phase relation of the flux in the core of the electromagnet to the phase of the alternating E. M. F. is determined by the reactance and resistance of theexciting circuit of saidcore and can therefore be adjusted by adjusting said reactance or said resistance or both. Since the phase relationbetween the core flux and the alternating E. M. F. is under control as well as the phase relation between the vibration of the springs and the period of the flux, then it is clear that the desired phase relation between said vibration and said alternating E. M. F. canbe secured with the help of any or all of the adjustments which have just been described. When the desired phase relation has been secured the stop 6 can be adjusted so that the springs 11 and 5 remain in contact durmg a suitable time interval.

The exciting circuit is fed from that part of the transformer winding which is located between the terminals S, and S and comprises the coil 10 of the electromagnet, the battery 20 and the impedance 13. Thecharging circuit is fed from the coil of the transformer located between S and YS, and comprises the springs 5 and 11 with their contacts, the battery 20 and the impedance '13. The maximum instantaneous value of the voltage derived from the line should be chosen a little greater than the maximum' voltage of the battery to be charged. When the alternating voltage is in one direction it cooperates with the battery voltage in sending an exciting current through the coil 10 which sets up a comparatively large'fiux in the core 9 and attracts the armature 7.

When the voltage from the line opposes the voltage of the battery through coil 10 the flux set up in the core is .necessarily much smaller and the stiffness of the spring 11' carrying the armature is such that this smaller flux is insuiiicient to initiate the 'armature vibrations. The resultant pulsating voltage through coil 10 is represented by the curve PV in Fig. 4;,- and it will be seen that the spring vibrations will be initiated at the correct instant whether the positive battery pole is connected to the terminal 16 or the terminal 17'. 4

The coil 10 takes a discharging current from the battery 20. But since this coil is made up of a number of turns of fine wire of high resistance the discharging, current is small in comparison with the charging current and the net result of the operation of I the device is an increase of the energy stored 1 a in the battery.- It will be seen that should the alternating current from the source be interrupted for any reason, a sinall'battery current will continue toflow through the coil 10 but the vibrationof the spring 1 1 115 will be stopped .thus preventing any possibility of'contactwith spring-5f and any discharge of the batterythrough the'low resistance charging circuit. The possibility of a rapid discharge of the battery is thus 1 obviated and itbecomes unnecessary to keep a close watch on the operation of the apparatus. I

Fig. 2 shows a device similar to Fig. 1, the only difierencebeing that the imped: 125 ance 13 is so placed as to be included in the charging circuit only, thus making the magnitude and the phase of the voltage at the terminals of the magnet coilsaindependent of the charging current. a j 3' 13c In Fig. 3 the battery voltage and the voltage derived from the separate coils 10 and 10 the effect upon the flux in same as in Fig. 1.

In Fig. 4 the curve AV ternating current voltage derived from the line by means of the transformer; the line DV shows the battery voltage and the curve PV the pulsating voltage which is the resultant of the alternating current voltage and thevoltage of the battery. The flux in the core 9 is represented by the curve F and is here shown as varying from zero to a certain value in a positive direction. As a respectively but the core 9 is the represents the alcan be disregarded. The vibration of the springs is represented by the curve S and the shaded portions show, the time of contact between the springs during which time t e charging current C flows.

I will now give a detailed explanation of the operation of my improved rectifier referring particularly to Figs. 1 and 4. Asthe armature Fig. 1, consider the instant when the positive alternating secondary of the transformer is at its maximum and is directed from S to 8,. Assume (2) that the battery the terminal 17 through the battery 20 to thealternating current voltage, plus the'dire'ct current voltage, 2'. e., the pulsating voltage, will have reached its positivemaximum at the instant under consideration. Assume (3), that the impedance of the excitingcircuit is such that the flux lags 90 degrees behind the pulsating E. M. F., then the maximum value of the pulsating flux will be reached one later than the positive'maximum of the alternating voltage. Assume (4) that the resultant natural frequency of vibration of the two springs is such as to cause the spring vibration to lag 90 degrees behind the flux and half a period after the ositive maximum of the alternating F. and 'a'fter the instant first considered. When the armature is nearest to the core 9 the alternating current voltage has reversed and 'has reached its negative maximum. The-pub sating voltage is now due to the difference between thealternating and direct current E. M. F.s and the pulsatingfiux is about half of its maximum intensity. When, 90 degrees later the armature has reached the initial position on its return vibration the alternating current voltage is zero.. The pulsating voltage is consequently equal to the direct current voltage and the flux is zero or negative.

line are applied to preaches its maximum but voltage is directed from quarter of a period combination with e armature 7 will be in its nearest When the voltage and is beginning to'exceed the same) t the same'time the pulsating voltage apis due solely to the sum of the alternatin the two parts, of the transformer secondary. The pulsating flux is increasingandjhas initial position,

as just described is repeated.

Should the battery connections to the ter minals 16 and 17 be reversed then'the maximum of the pulsating flux coincides with the negative maximum of the alternating E. M. F. and the armature will startto vibrate one half of a period later and the charging circuit will be closed one half of a period later, thus reversing the ,polarity of the charging M It is apparent therefore, that it is immaterial whether the. positive battery terminal is connected to the terminal 16 or to the terminal 17 of the apparatus, since the latter will always so operate as tosupply a charging current of greater value than the gischarging current which is permitted to claim as new and desire to secure'by Letters Patent of the United States is In an alternating current'rectifier, the a source of alternating current, of a transformer, an electro-magnet connected to said source through said transformer, a circuit closer to the phase of the alternating E. M. F., said circuit closer, when at rest, being in its open position, and a sourceof direct current connected to supply an to the electro-magnet current is flowing.

2. In an alternating current rectifier, the combination with current, of a. transformer connected thereto, an eleetro-magnet eenneeted t6 said trans- Having fully described my invention What T3 accumulator being in circuit an accumulator circult including said bration vapproxinjiating alternatingcurrentbut sufficiently different therefrom that the phase of the actual vibraformer, a vcircuit closer operated by said magnet and having a natural frequency of vibration approximating the frequency of the alternating current but sufliciently different therefrom that the phase of the actual vibration of the armature resulting from the influence of the exciting flux of the magnet and the armaturesnatural frequencyshall be substantially in opposition to the phase of the alternating E. M. F.,-said circuit closer, when at rest, being in its open position, anaccumulator to be charged, said withv acoil of the electro-magnet and supplying an uninterrupted direct'current to said coilwhen no alternatingecurrent'is flowing.

3; In a currentrectifying' apparatus, the combination with an alternating current source, of a transformer, an 'e lectro-magnet, to, be'charged, a charging transformer and said accumulator, an armature operated by said electro magnet for closing said charging circuit and having a natural frequency of vi tion-ofithe armature resulting from the in fiuence of the excitingflux of the magnet and thearmatures natural frequency sh all be substantially in opposition to the phaseof the alternating v E. M. F, and a permanently closed exciting circuit includingthe accumulator and a winding of the electro-magarmature when -positioned to make electrical'fconta'ctthere-- ,with at intervals when the armature'is viv i but positioned to 1 fee .cnetl, 1

vibrating. v

- -6 .JA current rectifying ap aratus com prising the combination with a source of ternating current, of a transformer,

4:. current rectifying apparatus comprising-the combination with a source of alternatingcurrent of a transformenan elecotro-magnet connected thereto, a spring mounted armature voperated byfsaid v magnet, a second spring in. electrical connection with the transformer and out of: contact-with said thearmature is at rest but brating.;. w :v; c ,r

27.5. A current rectifying apparatus comprising the combination with 'a source-ofalternat1ng current, of a; transformer, an -1 f mounted armature anatural frequency v the'freq'uency of the second spring connected to the sourceof al electro-magnet connected thereto, a. spring for said magnet having alternating current, a

ternating current and out ofcontact with said armature when the armature isat rest therewith at an elec' I tro-magnet connected thereto, aspringmountedarinature for said magnet, a second spring outofycontact with said armature the frequency of the mounted armature f natural frequency ofvibration-less than therlfrequency-ofthe alternating current,- a second spring normally out of contact with said, armature but'positioned to contact with it said second of vibrationless, than make electrical contact. intervals when the armature source,

- "i'provided with two 001150116 iasneee greater than the frequency of the alternating current, and an accumulator in'circuit with the armature.

v 7 A current rectifying apparatus comprising the combination with a source of alternating current, of a transformer, an electro-Inagnet connected thereto, a springmounted armature for said magnet having a natural frequency of vibration less than the frequency of the alternating current, a second spring out of contact with said. armature when the armature is at rest, -to contact therewith at intervals when the armature is vibrating, said second spring having a natural frequency of vibration greater than the frequency of the alternating current, and an accumulator to be charged, said armature and said electromagnet being but positioned I connectedto the accumulator in parallel cirmagnet for'closing the charging circuit, 531 6.

a-natural frequency of v1- bration approximating to but beingappreciably difierent fromthe frequency of the alternating current, and a permanently armature having an electro-magnet,

closed exciting circuit including the accumulator anda winding of the 5 electroma'gnet. 1 V 9. .A current rectifying. apparatus cointernatmg current, of'a transformer, an electro-magnet connected "thereto, a spring. for'said magnet having a during part of its vibration, spring making contact with sald armature onlywhen the armature has rebounded away from the electro-magnet, and an accumulator to be'charged, Y "'tro magnet said armature fcombination with v of a-transformer, an electro-magnet,

connected with the transformer, an accumulator to be charged, a charging circuit including said transformer and said accumu lator,

an armature operated by said electroof which is prisin'g the combination with a source of alp andsaid elecbeing connected to the accumulator in parallel circuits. 10;"In a current rectifying apparatus, the an alternating current magnet-for closing sa d charging circuit,"

' said armature having a natural'frequency 'preciably d1 erentifrom the frequency of thealternating current, and a permanently vibration approximating to but beingapclosed exciting circuitincl'uding the accumulator and the second winding of the electromagnet.

11. current rectifying apparatus comprising a transformer, an electro-magnet provided with two coils one of which is connected-to the transformer, a spring mounted armature for said magnet, a second spring connected 'to the transformer and out of contact'with the armature, when said arma- :ture isat restbutpositioned to contact .7 vibrating, an accumulator to be charged,

7 said accumulator being connected to the second'coil of the electro-magnet.

therewith at intervals when the armature is 12. A current rectifyin apparatus comprising the combination with a source of alternatmg current, of a transformer, an electromagnet connected thereto, an armature operatedby said magnet and having one end free to vibrate, a spring in electrical" connection with said transformer and out of contact with said armature when the armature is at rest but positioned to make elec- 1,1a1,sse

tricfal contact therewith at intervals when the armature is vibrating.

l3. A current rectifylng apparatus comprising the combination Wlth a source of alternating current, of a transformer, an elec greater than the frequency of-the alternating current, and an accumulator to be charged, said armature and said electromag net being connected to the accumulator parallel circuits. 1

In testimony whereof, I-have hereunto set my hand and aflixed my seal in the'presence of the two subscribing witnesses, v

EDWIN G. BALLMAN. [L,s.] Witnesses: i M. L. FRANKLIN,-

W. O. LAYMAN. 

